It should come as little surprise, then, to see the Seattle Seahawks retain a league-low 66.1 percent of their players from last season. It should likewise make sense to see the NFC North champion Minnesota Vikings retain a league-high 94.4 percent over the same period.

The Indianapolis Colts (73.0 percent retained) and Philadelphia Eagles (74.6 percent) made quite a few changes this offseason. The Colts annually field one of the NFL's youngest teams while funneling massive amounts of cash toward their star players. The Eagles sought to get younger.

Rosters throughout the league will change significantly again as teams comply with 53-man limits in September.

The chart shows how many Week 17 starters, backups and players from injured reserve remain with their 2009 teams. The retention rate divides those totals by the sum of 53 plus all players who were on IR lists in Week 17. The starter totals can be somewhat misleading for teams that rested key players before the playoffs, but the retention rates apply equally. Every team had 53 players on its roster in Week 17.

In double-checking totals, I noticed that teams have parted with 107 of the 294 players listed on IR in Week 17. That works out to 63.6 percent retention for players who were on IR, compared to 82.1 percent retention for players who were on 53-man rosters. The total retention rate -- 79.4 percent -- reflects both sets of players.

The chart breaks down totals based on rosters I have updated through moves made Thursday. I also accounted for the Denver Broncos' reported release of quarterback Tom Brandstater, who was with the team in Week 17. I'm counting unsigned franchise players (Aubrayo Franklin) and unsigned restricted free agents as still being with their 2009 teams, based on the fact that their teams hold rights to them.

San Francisco (.833): The 49ers like their team and they have been proactive in re-signing younger players. Continuity has been a top priority and that shows in the totals. The 49ers' retention rate fell because the team has not brought back five of the seven players it listed on IR in Week 17 (Thomas Clayton, Walt Harris, Tony Pashos, Ricky Schmitt and Jeff Ulbrich).

St. Louis (.773): It's a little surprising, on the surface, to see the rebuilding Rams rank second only to the 49ers in retention rate within the division. The Rams made massive overhauls last offseason, however, so there were fewer moves to make in recent months. Only the Lions and Baltimore Ravens brought back more players from IR, a total that could grow if Oshiomogho Atogwe re-signs. How well some of those players recover and hold up will be important for the Rams.

Arizona (.702): The turnover in Arizona has been documented thoroughly. Only Seattle has fewer players back from Week 17.

Seattle (.661): New coach plus new general manager plus a mandate for change leaves the Seahawks with only 39 players on their roster from Week 17 (counting those listed on IR). Every other team in the league has more. The league average is 49.4 players back.